Help: primary production

Hi, I'm a PhD student and I'm working on the secondary production in
sewage lagoons.
As I needed primary production data to analyse the seasonal succession of
plankton, I used the
"dark and light bottle" method.However, (as I'm a zoologist), I wander if
all the steps that I
followed are correct...
Step 1: I measured the variation of the oxygen content in bottles incubated
at 5 depth (Surface,
20 cm, 50 cm, 100 cm and 200 cm) during four hours around noon. Dark bottle
incubation was also
made during the same period.
During the incubation period, I also measured the total Irradiance
(Einstein by sqare meter).
Step 2: The oxygen quantities (produced by hour and by litre) were
converted into fixed carbon
(by hour and by litre) by multiplying by 0.375. (APHA 1985))
Step 3: I calculated the production by hour and by square meter for the
whole water column by
integrating the production measured at the different depth
Step 4: I multiplied the production by hour and by square meters by the
ratio "Total Irradiance
during the day/Total irradiance during the incubation".
Any remarks, (even on the spelling or grammar !), are wellcomed.
Thank you very much in advance.
Henry-Michel CAUXHIE
PhD Student UNIVERSITY OF LIEGE BELGIUM